The present invention is related to a damping and muffling structure for EL cell, and more particularly to a damping and muffling structure that is able to minify or even eliminate the vibration and noise caused by electromagnetic interference (abbreviated into EMI hereafter) created by A.C. electric field.
The conventional electroluminescent cell (EL cell) is a thin sheet and mainly used as backlight cell of PDA, mobile phone, etc. FIG. 5 shows a conventional EL cell composed of a transparent substrate 81, a front electrode layer 82, a lighting layer 83, an inducing layer 84, a back electrode layer 85 and an insulating layer 86. By means of a driving circuit, an AC voltage is applied to the front and back electrode layers 82, 85 to make the lighting layer 83 emit light.
When AC electric field acts on the inducing layer 84, due to EMI effect, the charge will accumulate on the inducing layer 84 to create surface energy conservation effect. The surface energy conservation effect will make uneven charge distribution on the inducing layer 84 and create piezoelectric effect. The piezoelectric effect will lead to vibration of the EL cell to emit noise. This affects the quality of the EL cell or even interferes with the driving of the LCD module.
In order to solve the problems of vibration and noise of the conventional EL cell caused by AC electric field, generally the EL cell is backed to increase the thickness thereof so as to minify the vibration and noise. Alternatively, the EL cell is tightly attached to the circuit board to reduce vibration and noise.
However, the EL cell applied to small-size electronic products such as mobile phones is limited in thickness specification. Therefore, the backing will lead to excessive thickness. On the other hand, the EL cell can be attached to the circuit board to reduce over 60% noise. However, it is difficult to assemble the module and the use of double-face tape will lead to increased cost.